diff --git a/test/built-ins/Temporal/PlainDate/prototype/weekOfYear/validate-calendar-value.js b/test/built-ins/Temporal/PlainDate/prototype/weekOfYear/validate-calendar-value.js
index f8bcc7ecce9..0033b10161e 100644
--- a/test/built-ins/Temporal/PlainDate/prototype/weekOfYear/validate-calendar-value.js
+++ b/test/built-ins/Temporal/PlainDate/prototype/weekOfYear/validate-calendar-value.js
@@ -8,7 +8,6 @@ features: [Temporal]
 ---*/
 
 const badResults = [
-  [undefined, TypeError],
   [null, TypeError],
   [false, TypeError],
   [Infinity, RangeError],
diff --git a/test/built-ins/Temporal/PlainDate/prototype/yearOfWeek/validate-calendar-value.js b/test/built-ins/Temporal/PlainDate/prototype/yearOfWeek/validate-calendar-value.js
index 5a44767f6b5..e8f682dad2f 100644
--- a/test/built-ins/Temporal/PlainDate/prototype/yearOfWeek/validate-calendar-value.js
+++ b/test/built-ins/Temporal/PlainDate/prototype/yearOfWeek/validate-calendar-value.js
@@ -8,7 +8,6 @@ features: [Temporal]
 ---*/
 
 const badResults = [
-  [undefined, TypeError],
   [Infinity, RangeError],
   [-Infinity, RangeError],
   [Symbol("foo"), TypeError],
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/weekOfYear/validate-calendar-value.js b/test/built-ins/Temporal/PlainDateTime/prototype/weekOfYear/validate-calendar-value.js
index e8aeb1d742e..69ff6a2c5ce 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/weekOfYear/validate-calendar-value.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/weekOfYear/validate-calendar-value.js
@@ -8,7 +8,6 @@ features: [Temporal]
 ---*/
 
 const badResults = [
-  [undefined, TypeError],
   [null, TypeError],
   [false, TypeError],
   [Infinity, RangeError],
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/yearOfWeek/validate-calendar-value.js b/test/built-ins/Temporal/PlainDateTime/prototype/yearOfWeek/validate-calendar-value.js
index d80ce15fa1c..0efa0075acb 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/yearOfWeek/validate-calendar-value.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/yearOfWeek/validate-calendar-value.js
@@ -8,7 +8,6 @@ features: [Temporal]
 ---*/
 
 const badResults = [
-  [undefined, TypeError],
   [Infinity, RangeError],
   [-Infinity, RangeError],
   [Symbol("foo"), TypeError],
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/weekOfYear/validate-calendar-value.js b/test/built-ins/Temporal/ZonedDateTime/prototype/weekOfYear/validate-calendar-value.js
index 9d6f448656e..fe3ba667d7c 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/weekOfYear/validate-calendar-value.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/weekOfYear/validate-calendar-value.js
@@ -8,7 +8,6 @@ features: [Temporal]
 ---*/
 
 const badResults = [
-  [undefined, TypeError],
   [null, TypeError],
   [false, TypeError],
   [Infinity, RangeError],
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/yearOfWeek/validate-calendar-value.js b/test/built-ins/Temporal/ZonedDateTime/prototype/yearOfWeek/validate-calendar-value.js
index 64a027b2dd7..6b87e8a8b25 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/yearOfWeek/validate-calendar-value.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/yearOfWeek/validate-calendar-value.js
@@ -8,7 +8,6 @@ features: [Temporal]
 ---*/
 
 const badResults = [
-  [undefined, TypeError],
   [Infinity, RangeError],
   [-Infinity, RangeError],
   [Symbol("foo"), TypeError],
diff --git a/test/intl402/Temporal/Calendar/prototype/weekOfYear/non-iso-week-of-year.js b/test/intl402/Temporal/Calendar/prototype/weekOfYear/non-iso-week-of-year.js
new file mode 100644
index 00000000000..f36305b29a2
--- /dev/null
+++ b/test/intl402/Temporal/Calendar/prototype/weekOfYear/non-iso-week-of-year.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.weekofyear
+description: >
+  Temporal.Calendar.prototype.weekOfYear returns undefined for all 
+  non-ISO calendars without a well-defined week numbering system.
+features: [Temporal]
+---*/
+
+// Gregorian calendar has a well defined week-numbering system.
+
+let calendar = new Temporal.Calendar("gregory");
+const date = { month: 1, day: 1, year: 2024, calendar};
+
+assert.sameValue(calendar.weekOfYear({...date}), 1);
+
+calendar = new Temporal.Calendar("hebrew");
+const nonisodate = { month: 1, day: 1, year: 2024, calendar};
+
+assert.sameValue(calendar.weekOfYear({...nonisodate}), undefined);
diff --git a/test/intl402/Temporal/Calendar/prototype/yearOfWeek/non-iso-week-of-year.js b/test/intl402/Temporal/Calendar/prototype/yearOfWeek/non-iso-week-of-year.js
new file mode 100644
index 00000000000..4337ed0918e
--- /dev/null
+++ b/test/intl402/Temporal/Calendar/prototype/yearOfWeek/non-iso-week-of-year.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.yearofweek
+description: >
+  Temporal.Calendar.prototype.yearOfWeek returns undefined for all 
+  non-ISO calendars without a well-defined week numbering system.
+features: [Temporal]
+---*/
+
+// Gregorian calendar has a well defined week-numbering system.
+
+let calendar = new Temporal.Calendar("gregory");
+const date = { month: 1, day: 1, year: 2024, calendar};
+
+assert.sameValue(calendar.yearOfWeek({...date}), 2024);
+
+calendar = new Temporal.Calendar("hebrew");
+const nonisodate = { month: 1, day: 1, year: 2024, calendar};
+
+assert.sameValue(calendar.yearOfWeek({...nonisodate}), undefined);
diff --git a/test/intl402/Temporal/PlainDate/prototype/weekOfYear/non-iso-week-of-year.js b/test/intl402/Temporal/PlainDate/prototype/weekOfYear/non-iso-week-of-year.js
new file mode 100644
index 00000000000..86c46b497d7
--- /dev/null
+++ b/test/intl402/Temporal/PlainDate/prototype/weekOfYear/non-iso-week-of-year.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindate.prototype.weekofyear
+description: >
+  Temporal.PlainDate.prototype.weekOfYear returns undefined for all 
+  non-ISO calendars without a well-defined week numbering system.
+features: [Temporal]
+---*/
+
+// Gregorian calendar has a well defined week-numbering system.
+
+let calendar = new Temporal.Calendar("gregory");
+const date = new Temporal.PlainDate(2024, 1, 1, calendar);
+
+assert.sameValue(date.weekOfYear, 1);
+
+calendar = new Temporal.Calendar("hebrew");
+const nonisodate = new Temporal.PlainDate(2024, 1, 1, calendar);
+
+assert.sameValue(nonisodate.weekOfYear, undefined);
diff --git a/test/intl402/Temporal/PlainDate/prototype/yearOfWeek/non-iso-week-of-year.js b/test/intl402/Temporal/PlainDate/prototype/yearOfWeek/non-iso-week-of-year.js
new file mode 100644
index 00000000000..e378c0884c4
--- /dev/null
+++ b/test/intl402/Temporal/PlainDate/prototype/yearOfWeek/non-iso-week-of-year.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindate.prototype.yearofweek
+description: >
+  Temporal.PlainDate.prototype.yearOfWeek returns undefined for all 
+  non-ISO calendars without a well-defined week numbering system.
+features: [Temporal]
+---*/
+
+// Gregorian calendar has a well defined week-numbering system.
+
+let calendar = new Temporal.Calendar("gregory");
+const date = new Temporal.PlainDate(2024, 1, 1, calendar);
+
+assert.sameValue(date.yearOfWeek, 2024);
+
+calendar = new Temporal.Calendar("hebrew");
+const nonisodate = new Temporal.PlainDate(2024, 1, 1, calendar);
+
+assert.sameValue(nonisodate.yearOfWeek, undefined);
diff --git a/test/intl402/Temporal/PlainDateTime/prototype/weekOfYear/non-iso-week-of-year.js b/test/intl402/Temporal/PlainDateTime/prototype/weekOfYear/non-iso-week-of-year.js
new file mode 100644
index 00000000000..1eb4e566bb6
--- /dev/null
+++ b/test/intl402/Temporal/PlainDateTime/prototype/weekOfYear/non-iso-week-of-year.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindatetime.prototype.weekofyear
+description: >
+  Temporal.PlainDateTime.prototype.weekOfYear returns undefined for all 
+  non-ISO calendars without a well-defined week numbering system.
+features: [Temporal]
+---*/
+
+// Gregorian calendar has a well defined week-numbering system.
+
+let calendar = new Temporal.Calendar("gregory");
+const date = new Temporal.PlainDateTime(2024, 1, 1, 12, 34, 56, 987, 654, 321, calendar);
+
+assert.sameValue(date.weekOfYear, 1);
+
+calendar = new Temporal.Calendar("hebrew");
+const nonisodate = new Temporal.PlainDateTime(2024, 1, 1, 12, 34, 56, 987, 654, 321, calendar);
+
+assert.sameValue(nonisodate.weekOfYear, undefined);
diff --git a/test/intl402/Temporal/PlainDateTime/prototype/yearOfWeek/non-iso-week-of-year.js b/test/intl402/Temporal/PlainDateTime/prototype/yearOfWeek/non-iso-week-of-year.js
new file mode 100644
index 00000000000..35c1b13f18d
--- /dev/null
+++ b/test/intl402/Temporal/PlainDateTime/prototype/yearOfWeek/non-iso-week-of-year.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindatetime.prototype.yearofweek
+description: >
+  Temporal.PlainDateTime.prototype.yearOfWeek returns undefined for all 
+  non-ISO calendars without a well-defined week numbering system.
+features: [Temporal]
+---*/
+
+// Gregorian calendar has a well defined week-numbering system.
+
+let calendar = new Temporal.Calendar("gregory");
+const date = new Temporal.PlainDateTime(2024, 1, 1, 12, 34, 56, 987, 654, 321, calendar);
+
+assert.sameValue(date.yearOfWeek, 2024);
+
+calendar = new Temporal.Calendar("hebrew");
+const nonisodate = new Temporal.PlainDateTime(2024, 1, 1, 12, 34, 56, 987, 654, 321, calendar);
+
+assert.sameValue(nonisodate.yearOfWeek, undefined);
diff --git a/test/intl402/Temporal/ZonedDateTime/prototype/weekOfYear/non-iso-week-of-year.js b/test/intl402/Temporal/ZonedDateTime/prototype/weekOfYear/non-iso-week-of-year.js
new file mode 100644
index 00000000000..c5f23944169
--- /dev/null
+++ b/test/intl402/Temporal/ZonedDateTime/prototype/weekOfYear/non-iso-week-of-year.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.weekofyear
+description: >
+  Temporal.ZonedDateTime.prototype.weekOfYear returns undefined for all 
+  non-ISO calendars without a well-defined week numbering system.
+features: [Temporal]
+---*/
+
+// Gregorian calendar has a well defined week-numbering system.
+
+let calendar = new Temporal.Calendar("gregory");
+
+// Epoch Nanoseconds for new Temporal.PlainDateTime(2024, 1, 1, 12, 34, 56, 987, 654, 321, calendar);
+const date = new Temporal.ZonedDateTime(1_704_112_496_987_654_321n, "UTC", calendar);
+
+assert.sameValue(date.weekOfYear, 1);
+
+calendar = new Temporal.Calendar("hebrew");
+const nonisodate = new Temporal.ZonedDateTime(1_704_112_496_987_654_321n, "UTC", calendar);
+
+assert.sameValue(nonisodate.weekOfYear, undefined);
diff --git a/test/intl402/Temporal/ZonedDateTime/prototype/yearOfWeek/non-iso-week-of-year.js b/test/intl402/Temporal/ZonedDateTime/prototype/yearOfWeek/non-iso-week-of-year.js
new file mode 100644
index 00000000000..7e163fa529d
--- /dev/null
+++ b/test/intl402/Temporal/ZonedDateTime/prototype/yearOfWeek/non-iso-week-of-year.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.yearofweek
+description: >
+  Temporal.ZonedDateTime.prototype.yearOfWeek returns undefined for all 
+  non-ISO calendars without a well-defined week numbering system.
+features: [Temporal]
+---*/
+
+// Gregorian calendar has a well defined week-numbering system.
+
+let calendar = new Temporal.Calendar("gregory");
+
+// Epoch Nanoseconds for new Temporal.PlainDateTime(2024, 1, 1, 12, 34, 56, 987, 654, 321, calendar);
+const date = new Temporal.ZonedDateTime(1_704_112_496_987_654_321n, "UTC", calendar);
+
+assert.sameValue(date.yearOfWeek, 2024);
+
+calendar = new Temporal.Calendar("hebrew");
+const nonisodate = new Temporal.ZonedDateTime(1_704_112_496_987_654_321n, "UTC", calendar);
+
+assert.sameValue(nonisodate.yearOfWeek, undefined);